Signaling system



R. -A. HEISING sIGN'ALING SYSTEM Dec. 16, 1924 1,519,615

Filed June 5 1920 I f5 a nec. 1c, 1924.

sr'ras RAYMOND A. HEISING, OF EAST ORANGE,

TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,

Yoan.

Application led June 5,

To all whom it may' concern.'

Be it known that I, RAYMOND A. HEIsING, a citizen of the United States, residing at East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Signaling Syssignaling and equivalent systems which are For this purpose means are actance for the carrier hereinafter described.

An object of the invention is to provide a generator of modulated oscillations wherein `the side frequencies, which for some purposes constitute the useful components of a modulated carrier current, may be conveniently separated and utilized and wherein the unmodulated component of carrier frequency may be wholly or partly suppressed.

provided including a branch path of zero reactance and impedance .for current of the carrier frequency and of substantial impedance for the comploenents of currentcorresponding to the side quencies, which components are therefore caused to flow in another branch path wherein the energy may be utilized or Wherefrom it may be drawn for utilization. The circuit of zero resistance and reactance comprises, in a preferred form, another oscillator having a frequency equal vto the carrier frequency of the oscillator whose oscillations are modulated. The branch path'of zero refrequency is designed to have a proportionally great self-inductance and small capacity whereby the unbalanced reactance 'for the side frequencies is caused to be proportionally great.

From one aspect the invention comprises a plrality of oscillation nerators, each connected to a circuit to ba which a load circuit is connected. W'fhen the oscillations of part of the oscillators are modulated, the yload circuit terminals are unbalanced with respect to the side frequencies to a greater extent than with respect to the carrier frequency. Discrimination is thereby roduced whereb he component of carrier requency may wholly or partly sepanced points of NEW JERSEY, ASSIGNOR T0 WESTERN ELEC- A CORPORATION 0F NEW SIGNALING SYSTEM.

1920. Serial No. 386,743.

arated. Ordinarily it willbe sufficient to provide two oscillators and cause modulation of the oscillations of one thereof as hereinafter described.

An important feature of the invention resides in the employment of a plurality of thermionic or equivalent oscillators each having a tuned circuit inv series with and constituting a load circuit for the other. As herein described, each oscillator constitutes a zero resistance load circuit. Another important feature resides inthe useof a zero resistance circuit for separating the components of a complex current.

The invention also comprehends certain. features of a receiving system which may be combined in a transmitting system for duplex signaling so that certain elements perform useful functions both in transmitting and in receiving, or may be used independently.

The invention will be described in detail in connection with the accompanying drawings wherein Fig. 1 'is a clrcuit diagram representing a modulating system in accordance with the invention: Fig. 2'is a radio l transmitting system including the invention: and Fig. 3 comprises 1n one circult a transmitting and receiving system forv duplex operation.

In Fig. 1 are shown two oscillating systems, A and B. Each. system comprises a thermionic device 1, of the type including an electrically heated ilamentary cathode, an anode, and a discharge controlling element in the form ofa grid, located, in the present instance, between the anode and the cathode. A highly evacuated envelope encloses these elements. Thel electrodes and grids are respectively connected, in a manner well-known 1n the art, to tuned circuits, each consisting of capacities 2, inductances 3 and capacities 4.' These f-tuned circuits instead of being closed individually, each upon itself, are closed by connecting them both in a series circuit 5. Around the tuned circuit of the system B is shunted a tuned circuit 6, including capacity 7 and inductance 8. A suitable outputl line or load circuit 10 is coupled to the circuit 6, in any suitable manner, as by including coil 11 therein and electromagnetically coupling the coil 11 to the coil 8. Means are provlded for causing the system A to generate modulated oscillations. Thismay be accomplished by producing low lio ' `actance for the osci system A and B ofFig. 1 s

I system A. Furthermore, since the system .B is also an oscillator the path 2, 3, 4 will ble or zero resistance for Vthe ations generated by system'A.

be of negli carrier osci Since the circuit 6 is in effect connected div unbalan ly differing therefrom,

y cordance with lower frequency si ali variations s,- there will, in general, ng

rectly across points a, 'bof the circuit 5, across which no difference of otential exists, becausethe generators are a justedto nor# mally generate equal voltages, littlecurrent will flow in the circuit 6. Let the v ath'2,- 3, 4 bea stiii:` resonant circuit and lt e cir-4 cuit 6 a loose resonant circuit, that is, al-

though the vcircuits are tuned to the sainev will have relatively small mductance and large capacity while' frequency, 'the circuit 6 the path 2, 3, 4 will have relatively large inductance and small or equivalent low frequency variations are produced-in the microphone circuit.' 12, the oscillations of the system A will be -modulated. As is known in the art, if `oscillations of carrier frequency p, be modulated in iacroducedacomposite current com' risi pthe uenciesp, p-s and +r, o whi 'the two latter are knownas tl e side frequencies and the former as the resistance and reactance for the unmodulated com reactance foruencies slight- `the side frequencies will be shunted to a large extent through circuit 6 and impressed-upon the work circuit 10. However, only a small vproportion of the unmodulated l com nent will -pass through the circuit 6', t is proportion depending vin general, upon the effective resistance of this circuit.

In Fi 2, the system A is caused to 'l ate mo vulated. oscillations in a d i erent manner than in 1 namely by' vary' thev plate potential acrdss the tube 1 in cordanceA with siial'ng frequency variations in a microp one circuit 12. vInxthis system,4 commonly known as the constant current modulation system, the microphone circuit 12 acts to' ,v vacuum 'tube 14, these elements together constituting alvariable impedance system C. fl'he variable impedance systemis connected in shunt tothe system A with res capacity. `When speech c v unmodulated com ponent., -Since` th'e path 2, 3,4 is of zero nent'but has a relatively largel nerl ary. the impedance of a l to thef i source of current 15 and the sign choke tailed description will be unneceary. In t general, however, the system A may comprise any source of vmodulated carrier fre'- quency oscillationsrf'lhe system B likewise comprisesl anoscillation generating system of a known type wherein avacuum tube 1, supplied with space current from source117 tions in the circuit comprising the .capacityl 4,` inductance coil .3 and capacity 2.' For radio transmission a suitable antenna iscon-4 nected across the ,points a, b which'cor` respond to the points a, b of Fig. 1. With both vsystems A and B an instant when no si als are be 4'transf mitted,` oscillations wi lbe produce `in the closed circuit comprisin the vsets of'jel'ements- 2, 3, and 4. lCorresponding toFi 1, the path 2, 3, 4, of the system B is a sti y resonant tuned circuit of zero impedance tothe carrier frequency. When the oscillations of the 'system are modulated, points- 11,6 will become unbalanced ywith respect to the side frethrough a choke coil 18, produces oscill'a'fej't'5l-` operating, b ,ut during" quencies thereby causing the 'energy of the side frequencies to be transferred-to the circuit 6 and radiated. e v 'n y The duplex radio station s hown in '.-Fig. 3, comprises transmitting means similar to the arrangement of Fig. 2. There is provided, however, additional means forreceiving, consisting of the tube 19, whose gridis con'- nected in parallelwith the ls ourcle and the choke 16. A' condenser'20 keeps direct curl' rentfrom the source 15 out of the gridA circuit vof the" tube 19. Between the grid and the filament of the tube .19 is connected a highly resistive leak ypath 21. Suppose now, -that side'frequencies, eitherwithr'or without an unmodulated component, are being re`- ceived by the antenna 6. Sincethe .tuned circuit 2, 3, 4 of system A is a stilly resonant circuit while the circuit 2, 3, 4, of system B is aloose resonant circuit, ia proportionally lio greater part of the received energy will pass into the system A. If, however, the .tuned circuits of thesystems A andtBy are identical, then approximately one-halfof the received energy will pass into each system. 'v In either case, however, the energy of. the received side frequencies which. -asses into the system A will be impr upon the grid circuit of the tube y1. Owingto the detecting action of the tube 1, beats will be reduced between the carrier frequenc' prouced 'by system A and the 'receive 'side frequencies.v If the oscillation frequency of i the system A is, in the case of telephony, equal to the carrier fvreqiency of the received signals, these beats wi speech tele phy,v however, where the of les stein A is beats w" be of a l frequency properly adjusted, these suitab e audible frequency.

be in theform, of u'eiicy currents. In' the case of Y p the beat component in the output circuit of tube l, will be impressed upon the grid circuit of the amplifying tube 19 and the resulting signal is received in any suitable manner, as for example, by listening to a telephone receiver connected to the output circuit of the tube 19. The circuit 6 is not necessarily an antenna or some form of load circuit, but may loe a transmission line or a filter circuit connected with an antenna or a transmission line and may include repeaters or other similar apparatus. f

W'hile certain complete systems embodying the features of the invention are described hereimthe invention is not limited to any particular embodiment but all or part of the features thereot'imay be utilized in other systems. The novel features believed to be inherent in the invention are defined in the appended claims.

lVhat is claimed is:

l. A modulating system comprising an oscillator, means for causing the oscillator to generate modulated current, a plurality of paths forV the passage of said current, one of said paths including a stiflly resonant circuit of zero react-ance and resistance for the unmodulate-d component' of the modulated current, and another of said paths includ.- ing a. loosely resonant circuit timed to the same frequency.

2. A modulating system comprising a source of voltage having the wave form of a modulated current having an unmodulated component, a pair of paths connected in parallel to said source, one of said paths comprising a stiflly resonant circuit of zero reactance and resistance for the unmodulated component of the modulated current, and the other of said paths including a loosely resonant circuit tuned to the same frequency.

3. A modulating system comprising a source ot'l voltage having the wave form of a modulated current including an uumodulated component, a plurality of paths resonant to the same requ'enc connected in parallel with respect to said source, said paths being of dill'erent impedance to the side frequencies of the modulated current.

4. A high frequency circuit in combina- The energy of tion with a plurality of electron discharge oscillation generators having reactive paths included in series with respect to said high frequency circuit.

5. A circuit tuned to a given frequency in combination with a plurality of individually complete self-synchronizing oscillation generators having reactance elements in er"- fective serial relation to said circuit.

6. ln combination, a series circuit, and a plurality of oscillation generators arranged in series with and constituting parts of said circuit, each said generator comprising a series path tuned to have substantially zero reactance for current of a given frequency to be generated.

7. A system comprising a series circuit, a plurality of independently tuned portions in said circuit, said portions being resonant to the same frequency, a plurality of thermionic devices, and an input circuit and an output circuit for each device, the input circuit and output circuit of each device being connected to one of said portions respectively.

8. A modulating system comprising a generator for producing oscillations of a given carrier frequency, means associated therewith to cause modulated oscillations to be generated thereby, a path of zero reactance and resistance for current of `the carrier frequency connected to said generator, and a branch pat-h in shunt to said first mentioned path, said branch path being similarly tuned but of looser resonance.

9. A modulating system comprising a pair of oscillation generators connected to generate oscillations in a closed circuit, a load circuit connected between two points in said closed circuit, and means for causing variations in amplitude of the voltage produced by one of said oscillators.

10. A modulating system comprising two generators of alternating current included in a closed circuit, a path connectin two normally balanced points on said circuit, and means for disturbing the balance by causing` one generator toproduce variable oscillations.

1l. In combination two electron discharge devices, each having an anode, a cathode and a discharge controlling element, and appropria-te means including circuits having included therein a tuned path whereby each functions as an oscillation generator, the tuned path of each generator being in a circuit through which the other tends to drive current.

l2. system comprising two sources o high frequency oscillations, means 'for modulating the oscillations from one of said sources, means 'for radiating the modulated oscillations, said radiating means constitutin a receiving means for impressing received oscillations upon said sources, one of said sources being selective ot the received oscillations, said source functioning to combine the energy of received oscillations impressed thereon `with the generated oscillations, and indicating means for indicating the signals resulting from said combination.

13. A system comprising two sources of oscillations, a source of signal waves, said sources of oscillations cooperating tc transmit waves varied in accordancewith said signal waves, receiving means comprising one of said sources of oscillations, and indieating means lto indicate the signals received by said receiving means.

lOl)

14. An electrical network` comprising three branches terminating in a common pair of points, said branches being similarly tuned, at least one of said branches being of zero effective resistance for current of a certain frequency and one of said branches havlng a flatter resonance\character1st1c than another.

other with respectto said circuit, said paths being similarly tuned but having different ratios of self-inductance and capacity.

17 A system for separating the modulated and unmodulated components of a modulated current which comprises a source of modulated current and a pair of paths tuned-l to the same frequency but-having different effective values of s'elf-inductance and capacity, said paths being connected in vparallel to each other with respect to the source of modulated current.

18. The method of selectively 'receiving a i modulated Wave which comprises impress` y ing thel wave upon circuits connected parallel to each other with -respect to the source of said modulated wave, said circuits being resonant tothe `same frequency but of different impedance to certain frequency components of the modulated wave.

19. The method of selectively separating the components of a complex current which comprises passing the current through a plurally branched circuit, one `branch of which ,has zero effective resistance.

20. A transmitting system comprising a source of high frequency oscillations and ltwo parallel paths of constant effective resistance continually connected to said sourcel and tuned to the same frequency,y the ratio of self-inductance to capacity being different in the two paths, and means for transmitting signals while maintaining the state of continuity of said paths with respect to said source.

21. A radio system comprising a receiving antenna for receiving modulated carrier waves, means including a circuit for supplying and means for combining locally produced Waves of the carrier frequency of the incoming waves with said yincoming waves, and means for preventing the supplied locally produced .waves from reaching the antenna and being radiated.

In witness whereof, I hereunto subscribe my name this 27th day of Ma RAYMOND A. i f 

